Bio 113 notes- scientific method and measurement (lecture 1)

Science is not memorizing facts

this is the opposite of what science is

Science definition

• asking a scientist what they do and they will answer the question

• its a tool, a useful tool but nothing more

• a way of asking questions

Observations/data

• observations or data provide the material to ask the question

• others may have already asked the question you have (what do they find)

• using what’s already known (how does it fit together)

Inductive reasoning

a logical skill which builds a generalized result from a series of specific observations

Hypothesis

preliminary answer to a question based on both data and what others have found

Deductive reasoning

using general information to make a specific prediction; required to design on experiment

is the experiment consistent with the data?

if yes hypothesis confirmed if no the hypothesis may be changed

Theory/scientific law

• Isaac newton came up with laws of motion: not correct at small scales

• anyone can come yo with a theory just as anyone can design an experiment to disprove an idea

• predictions and experiments may be very specific or very general

Experiements and theories may be flowed

• new data can change even the most well regarded ideas ir experiments may fail for technical reasons

Technology

• way of solving problems using scientific results

• applied science

• ex: finding a gene that causes a disease is science and developing a treatment is technology for a disease

• society decides what we should do with science and technology rather than what we do

• earth has gotten warmer over the last 125 years is an example of observed data

Measurement/units

• everything in science is measured in a metric system

• conversions are easy

• all units relate to each other

• units scale equally using prefixes and factors of 10

Actual conversions

• 1 mL of water=1g

• 1 cubic cm=1 mL

• density of water=1g/1mL

• water freezes at 0 degrees celsius

• water melts at 100 degrees celsius

• 1 calorie is energy needed to raise

• 1 mL of water=1 degrees celsius

• food calories are kilocalories

prefixes and factors of 10s

• P peta=10^15

• T Tera=10^12

• G giga= 10^9

• M mega=10^6

• k kilo=10³

• h hecto=10²

• dk deca=10^1

• dc deci=10^-1

• c centi=10^-2

• m milli=10^-3

• micro=10^-6

• n nano=10^-9

• p pico=10^-12

• f femto=10^-15

Units

• liters=volume

• meters=distance

• grams=mass

• energy=calories (not joules)

• temperature=kelvin (centigrade or celsius+273.15)

Elements

substances which are short of nuclear reactions such as as the sun and and super means therefore cannot be changed by chemical means

Compounds

• mixtures of 1 or more elements which can be changed and recombines

• provided the elements themselves are conserved

Properties of an element

• atoms are the smallest unit of an elements which retains the properties of that element

• electrons are mobile, whereas the nuclei don’t change

• the number of protons in a nucleus determines what an atom is

• the number of neutrons determines the isotope of the element

Covalent bond

• formed by two atoms sharing an electron

• not just any electron can be shared

• only electrons on the outer shell or orbital may be shared between atoms

Valence number

number of electrons that an atom may share

Atomic number

number of protons determines the position in the periodic table

Atomic mass

what differs between isotopes of the same element

Single bond

a chemical bond where two atoms share one pair of electrons

Double bond

a stronger chemical bond where two atoms share two pairs of electrons

Covalent bonds are shown as

• lines between atoms

• each line is equal to 2 electrons one from each atom

• lone paid str electrons in the outer shell are not shared between atoms

• atoms which are more electronegative like the electrons more than others

• electrons spend more time near the more electromagnetic atom giving a partial negative and partial positive charge

Electronegativity

an atoms ability to attract shared electrons towards itself when forming a chemical bond

hydrogen bonds

hydrogens are usual h-bond acceptors with lone pair containing atoms that are h bond donors

Ions

more electrons give C-0 charged atoms, fewer electrons give a positive charged atom and the number of protons never changes

Ionic bonds

• bonds between positive and negative charged ions (water helps stabilize charged ions)

• chemical reactions rearrange chemical bonds

• life is basically a regulated series of reactions

• depending upon what chemicals are able to interact, different products may be formed

Chemical equilibrium reaction

• reaction that can go in both directions

• change the conditions (temp, concentration, etc.) then the direction of reaction changes

Equilibrium

when the reaction moves at the same rate in each direction